In terms of usefulness, they are actually more useful than the bigass phones like the iPhone Max or S26 Ultra, and other comparable ones from various manufacturers. The outer screen is pretty small and very usable with one hand. There are a few multitasking options you can choose from once you unfold them. you can have two or four apps open at once if needed. They are also very good for watching videos. A huge number of smartphone users do spend a lot of time watching stuff on their screens.
The latest Samsung Z Fold 8 has become a huge success... its size appears to be even more ideal for one hand. the thinness and overall size of it once opened has essentially seemed like the perfect form factor for the latest generation of smartphone users.